This container can be pulled via:
  docker pull registry.opensuse.org/home/dcassany/elemental/classic/maintenance_6.2_fork/containers/rancher/seedimage-builder:1.8.1
  docker pull registry.opensuse.org/home/dcassany/elemental/classic/maintenance_6.2_fork/containers/rancher/seedimage-builder:1.8.1-2.5

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.